Rickroll

The nickname for a method of pranking whereby people will
post a link to something but the link actually goes to a You Tube video of Rick
Astley's song "I'm Never Gonna Give You Up." Also known as an
Internet meme, "Rickrolling" is a bait-and-switch because the URL can be masked so that the user cannot
determine the true source of the link without first clicking on it. Once a
person clicks on the link and is led to the web page, he or she is said to have
been "Rickrolled".

This term can also refer to playing the song loudly in
public in order to be disruptive.

The practice is said to have begun as an earlier prank
originating from the imageboard 4chan and was called duckrolling. A user
was "duckrolled" once he or she clicked on a link (such as a picture or news
item) and would instead be taken to a thread or a website containing an edited
picture of a duck on wheels. The first instance of Rickroll occurred on the
site's video game board, where a link to the Rick Astley video was claimed to
be a mirror of the first trailer for Grand Theft Auto IV (which was unavailable
due to heavy traffic). The joke was confined to 4chan for a very brief period
and then spread virally, becoming an Internet phenomenon. An April 2008 poll by
SurveyUSA estimated that at least 18 million American adults have been
Rickrolled.

For more examples, including the classic April Fools' Day
2008 Rickroll pranks, search for this term on Wikipedia below!